The present invention concerns a drive. A motion-transmission member in the form of a strap or belt wraps around both a belt-driving wheel and a belt-motion deflector. The belt either constitutes or can be fastened at the ends to constitute a continuous loop. A surface structure extends at least part-way along the belt. The surface structure extends approximately more than half-way along the belt when motion is transmitted back and forth. A matching structure extends along at least the contact surface of the belt-driving wheel. The structure on the surface of the belt-driving wheel fits into and engages the structure on the surface of the belt along the direction that force is being transmitted in.
Drives of this genus are primarily employed to move components back and forth along a limited stretch, to open and close a door panel for example. The mechanisms addressed herein, however, are not only those that move along a limited stretch or back and forth between two points. The drives employed for such purposes can transmit motion either by friction or by means of form-fit ("formschlussig") components, chains and cogged belts in particular. Form fit between part of the member attached to the component being moved on the one hand and the belt-driving wheel on the other is satisfactory for back-and-forth motions over limited stretches. A door panel for example can be operated by a motor-powered chain wheel if the wheel engages a chain-like section of a continuous-loop motion-transmission member that the panel is attached to.
The continuous loop makes it possible to avoid long stretches wherein no motion occurs, as in rack-and-pinion mechanisms for example.
One advantage of a drive with form fit is that it cannot slip. Another is the absolute precision, allowing of course for tensional distortion, with which the engaging members can be matched along the stretch in question. Driving force usually needs to be applied only between the output wheel and the belt-shaped motion-transmission member, when, specifically, the latter is directly fastened to the component being moved, which often happens when the motion is back-and-forth. It is on the other hand also possible to transmit the output from the drive by way of the belt-motion deflector, especially if the latter is a wheel, which can then be included if necessary in the interlocking engagement.